Materials for organic light emitting diode

ABSTRACT

Organometallic compounds comprising a phenylquinoline or phenylisoquinoline ligand having the quinoline or isoquinoline linked to the phenyl ring of the phenylquinoline or phenylisoquinoline, respectively, via two carbon atoms. These compounds also comprise a substituent other than hydrogen and deuterium on the quinoline, isoquinoline or linker. These compounds may be used as red emitters in phosphorescent OLEDs. In particular, these compounds may provide stable, narrow and efficient red emission.

The claimed invention was made by, on behalf of, and/or in connectionwith one or more of the following parties to a joint universitycorporation research agreement: Regents of the University of Michigan,Princeton University, The University of Southern California, and theUniversal Display Corporation. The agreement was in effect on and beforethe date the claimed invention was made, and the claimed invention wasmade as a result of activities undertaken within the scope of theagreement.

FIELD OF THE INVENTION

The present invention relates to organic light emitting devices (OLEDs).More specifically, the present invention is related to organometalliccompounds comprising a phenylquinoline or phenylisoquinoline ligandhaving the quinoline or isoquinoline linked to the phenyl ring of thephenylquinoline or phenylisoquinoline, respectively. The ligand alsocontains a bulky substituent on the quinoline, isoquinoline or twocarbon atom linker. These compounds may be used in OLEDs to providedevices with improved lifetime and color. In particular, these compoundsmay be especially useful as stable, narrow and efficient red emissivecompounds.

BACKGROUND

Opto-electronic devices that make use of organic materials are becomingincreasingly desirable for a number of reasons. Many of the materialsused to make such devices are relatively inexpensive, so organicopto-electronic devices have the potential for cost advantages overinorganic devices. In addition, the inherent properties of organicmaterials, such as their flexibility, may make them well suited forparticular applications such as fabrication on a flexible substrate.Examples of organic opto-electronic devices include organic lightemitting devices (OLEDs), organic phototransistors, organic photovoltaiccells, and organic photodetectors. For OLEDs, the organic materials mayhave performance advantages over conventional materials. For example,the wavelength at which an organic emissive layer emits light maygenerally be readily tuned with appropriate dopants.

OLEDs make use of thin organic films that emit light when voltage isapplied across the device. OLEDs are becoming an increasinglyinteresting technology for use in applications such as flat paneldisplays, illumination, and backlighting. Several OLED materials andconfigurations are described in U.S. Pat. Nos. 5,844,363, 6,303,238, and5,707,745, which are incorporated herein by reference in their entirety.

One application for phosphorescent emissive molecules is a full colordisplay. Industry standards for such a display call for pixels adaptedto emit particular colors, referred to as “saturated” colors. Inparticular, these standards call for saturated red, green, and bluepixels. Color may be measured using CIE coordinates, which are wellknown to the art.

One example of a green emissive molecule is tris(2-phenylpyridine)iridium, denoted Ir(ppy)₃, which has the following structure:

In this, and later figures herein, we depict the dative bond fromnitrogen to metal (here, Ir) as a straight line.

As used herein, the term “organic” includes polymeric materials as wellas small molecule organic materials that may be used to fabricateorganic opto-electronic devices. “Small molecule” refers to any organicmaterial that is not a polymer, and “small molecules” may actually bequite large. Small molecules may include repeat units in somecircumstances. For example, using a long chain alkyl group as asubstituent does not remove a molecule from the “small molecule” class.Small molecules may also be incorporated into polymers, for example as apendent group on a polymer backbone or as a part of the backbone. Smallmolecules may also serve as the core moiety of a dendrimer, whichconsists of a series of chemical shells built on the core moiety. Thecore moiety of a dendrimer may be a fluorescent or phosphorescent smallmolecule emitter. A dendrimer may be a “small molecule,” and it isbelieved that all dendrimers currently used in the field of OLEDs aresmall molecules.

As used herein, “top” means furthest away from the substrate, while“bottom” means closest to the substrate. Where a first layer isdescribed as “disposed over” a second layer, the first layer is disposedfurther away from substrate. There may be other layers between the firstand second layer, unless it is specified that the first layer is “incontact with” the second layer. For example, a cathode may be describedas “disposed over” an anode, even though there are various organiclayers in between.

As used herein, “solution processible” means capable of being dissolved,dispersed, or transported in and/or deposited from a liquid medium,either in solution or suspension form.

A ligand may be referred to as “photoactive” when it is believed thatthe ligand directly contributes to the photoactive properties of anemissive material. A ligand may be referred to as “ancillary” when it isbelieved that the ligand does not contribute to the photoactiveproperties of an emissive material, although an ancillary ligand mayalter the properties of a photoactive ligand.

As used herein, and as would be generally understood by one skilled inthe art, a first “Highest Occupied Molecular Orbital” (HOMO) or “LowestUnoccupied Molecular Orbital” (LUMO) energy level is “greater than” or“higher than” a second HOMO or LUMO energy level if the first energylevel is closer to the vacuum energy level. Since ionization potentials(IP) are measured as a negative energy relative to a vacuum level, ahigher HOMO energy level corresponds to an IP having a smaller absolutevalue (an IP that is less negative). Similarly, a higher LUMO energylevel corresponds to an electron affinity (EA) having a smaller absolutevalue (an EA that is less negative). On a conventional energy leveldiagram, with the vacuum level at the top, the LUMO energy level of amaterial is higher than the HOMO energy level of the same material. A“higher” HOMO or LUMO energy level appears closer to the top of such adiagram than a “lower” HOMO or LUMO energy level.

As used herein, and as would be generally understood by one skilled inthe art, a first work function is “greater than” or “higher than” asecond work function if the first work function has a higher absolutevalue. Because work functions are generally measured as negative numbersrelative to vacuum level, this means that a “higher” work function ismore negative. On a conventional energy level diagram, with the vacuumlevel at the top, a “higher” work function is illustrated as furtheraway from the vacuum level in the downward direction. Thus, thedefinitions of HOMO and LUMO energy levels follow a different conventionthan work functions.

More details on OLEDs, and the definitions described above, can be foundin U.S. Pat. No. 7,279,704, which is incorporated herein by reference inits entirety.

SUMMARY OF THE INVENTION

Organometallic compounds comprising a phenylquinoline orphenylisoquinoline ligand having the quinoline or isoquinoline linked tothe phenyl ring of the phenylquinoline or phenylisoquinoline,respectively, via a carbon linker are provided. The compounds alsocomprise a bulky substituent on the quinoline, isoquinoline, or linker.The compounds have the formula M(L₁)_(x)(L₂)_(y)(L₃)_(z).

The ligand L₁ is

The ligand L₂ is

The ligand L₃ is a third ligand.

Each L₁, L₂ and L₃ can be the same or different. M is a metal having anatomic number greater than 40. Preferably, M is Ir. x is 1, 2, or 3. yis 0, 1, or 2. z is 0, 1, or 2. x+y+z is the oxidation state of themetal M. R is a carbocyclic or heterocyclic ring fused to the pyridinering. R is optionally further substituted with R′. A, B, and C are eachindependently a 5 or 6-membered carbocyclic or heterocyclic ring. R′,R_(Z), R_(A), R_(B), and R_(C) may represent mono, di, tri, or tetrasubstitutions. Each of R₁, R₂, R₃, R₄, R′, R_(Z), R_(A), R_(B), andR_(C) are independently selected from the group consisting of hydrogen,deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy,aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl,aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof. At least one of R₁, R₂, R₃, R₄, and R′ is not hydrogen ordeuterium. Any two adjacent R₁, R₂, R₃, R₄, and R′ are optionally linkedto form an alkyl ring.

In one aspect, at least one of R₁, R₂, R₃, R₄, and R′ is an alkyl. Inanother aspect, R′ is not hydrogen or deuterium. Preferably, at leastone of R₁, R₂, R₃, R₄, and R′ is an alkyl having more than 2 carbonatoms. More preferably, at least one of R₁, R₂, R₃, R₄, and R′ isisobutyl.

In one aspect, L₃ is a monoanionic bidentate ligand.

In another aspect, L₃ is

and R′₁, R′₂, and R′₃ are each independently selected from the groupconsisting of hydrogen, deuterium, halide, alkyl, cycloalkyl,heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl,cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl,carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl,sulfonyl, phosphino, and combinations thereof. Preferably, R′₂ ishydrogen. More preferably, at least one of R′₁, R′₂, and R′₃ contains abranched alkyl moiety with branching at a position further than the αposition to the carbonyl group. Most preferably, at least one of R′₁ andR′₃ is isobutyl.

In one aspect, the compound has the formula:

R₅ and R₆ may represent mono, di, tri, or tetra substitutions. Each ofR₅ and R₆ are independently selected from the group consisting ofhydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl,alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl,alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester,nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, andcombinations thereof. At least one of R₁, R₂, R₃, R₄, and R₆ is nothydrogen or deuterium. m is 1, 2, or 3.

in another aspect, the compound has the formula:

R₅ and R₆ may represent mono, di, tri, or tetra substitutions. Each ofR₅ and R₆ are independently selected from the group consisting ofhydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl,alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl,alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester,nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, andcombinations thereof. At least one of R₁, R₂, R₃, R₄, and R₆ is nothydrogen or deuterium. m is 1, 2, or 3.

In one aspect, the compound is homoleptic. In another aspect, thecompound is heteroleptic.

Specific non-limiting examples of organometallic compounds comprising aphenylquinoline or phenylisoquinoline ligand having the quinoline orisoquinoline linked to the phenyl ring of the phenylquinoline orphenylisoquinoline, respectively, are provided. These compounds alsohave a bulky substituent on the quinoline, isoquinoline, or linker. Inone aspect, the compound is selected from the group consisting of:

Preferably, the compound is:

Additionally, a first device comprising a first organic light emittingdevice is provided. The organic light emitting device further comprisesan anode, a cathode, and an organic layer, disposed between the anodeand the cathode. The organic layer further comprises a compound havingthe formula M(L₁)_(x)(L₂)_(y)(L₃)_(z), as described above.

The ligand L₁ is

The ligand L₂ is

The ligand L₃ is a third ligand.

Each L₁, L₂ and L₃ can be the same or different. M is a metal having anatomic number greater than 40. x is 1, 2, or 3. y is 0, 1, or 2. z is 0,1, or 2. x+y+z is the oxidation state of the metal M. R is a carbocyclicor heterocyclic ring fused to the pyridine. R is optionally furthersubstituted with R′. A, B, and C are each independently a 5 or6-membered carbocyclic or heterocyclic ring. R′, R_(Z), R_(A), R_(B),and R_(C) may represent mono, di, tri, or tetra substitutions. Each ofR₁, R₂, R₃, R₄, R′, R_(Z), R_(A), R_(B), and R_(C) are independentlyselected from the group consisting of hydrogen, deuterium, halide,alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino,silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl,acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl,sulfinyl, sulfonyl, phosphino, and combinations thereof. At least one ofR₁, R₂, R₃, R₄, and R′ is not hydrogen or deuterium. Any two adjacentR₁, R₂, R₃, R₄, and R′ are optionally linked to form an alkyl ring.

The various specific aspects discussed above for compounds having theformula M(L₁)_(x)(L₂)_(y)(L₃)_(z) are also applicable to a compoundhaving M(L₁)_(x)(L₂)_(y)(L₃)_(z) that is used in the first device. Inparticular, specific aspects of L₁, L₂, L₃, A, B, C, R_(A), R_(B),R_(C), R_(Z), R, R′, R₁, R₂, R₃, R₄, R₅, R₆, R′₁, R′₂, R′₃, M, m FormulaIII and Formula IV of the compound having the formulaM(L₁)_(x)(L₂)_(y)(L₃)_(z) are also applicable to a compound havingM(L₁)_(x)(L₂)_(y)(L₃)_(z) that is used in the first device.

In one aspect, the first device is a consumer product. In anotheraspect, the first device is an organic light emitting device. In yetanother aspect, the first device comprises a lighting panel.

In one aspect, the organic layer is an emissive layer and the compoundis an emissive dopant. In another aspect, the organic layer furthercomprises a host. Preferably, the host is a metal 8-hydroxyquinolate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an organic light emitting device.

FIG. 2 shows an inverted organic light emitting device that does nothave a separate electron transport layer.

FIG. 3 shows a phenylquinoline or phenylisoquinoline ligand with thequinoline or isoquinoline linked to the phenyl ring of thephenylquinoline or phenylisoquinoline, respectively, and comprising abulky substituent.

FIG. 4 shows exemplary organometallic compounds comprisingphenylquinoline or phenylisoquinoline ligand with the quinoline orisoquinoline linked to the phenyl ring of the phenylquinoline orphenylisoquinoline, respectively, and comprising a bulky substituent.

DETAILED DESCRIPTION

Generally, an OLED comprises at least one organic layer disposed betweenand electrically connected to an anode and a cathode. When a current isapplied, the anode injects holes and the cathode injects electrons intothe organic layer(s). The injected holes and electrons each migratetoward the oppositely charged electrode. When an electron and holelocalize on the same molecule, an “exciton,” which is a localizedelectron-hole pair having an excited energy state, is formed. Light isemitted when the exciton relaxes via a photoemissive mechanism. In somecases, the exciton may be localized on an excimer or an exciplex.Non-radiative mechanisms, such as thermal relaxation, may also occur,but are generally considered undesirable.

The initial OLEDs used emissive molecules that emitted light from theirsinglet states (“fluorescence”) as disclosed, for example, in U.S. Pat.No. 4,769,292, which is incorporated by reference in its entirety.Fluorescent emission generally occurs in a time frame of less than 10nanoseconds.

More recently, OLEDs having emissive materials that emit light fromtriplet states (“phosphorescence”) have been demonstrated. Baldo et al.,“Highly Efficient Phosphorescent Emission from OrganicElectroluminescent Devices,” Nature, vol. 395, 151-154, 1998;(“Baldo-I”) and Baldo et al., “Very high-efficiency green organiclight-emitting devices based on electrophosphorescence,” Appl. Phys.Lett., vol. 75, No. 3, 4-6 (1999) (“Baldo-II”), which are incorporatedby reference in their entireties. Phosphorescence is described in moredetail in U.S. Pat. No. 7,279,704 at cols. 5-6, which are incorporatedby reference.

FIG. 1 shows an organic light emitting device 100. The figures are notnecessarily drawn to scale. Device 100 may include a substrate 110, ananode 115, a hole injection layer 120, a hole transport layer 125, anelectron blocking layer 130, an emissive layer 135, a hole blockinglayer 140, an electron transport layer 145, an electron injection layer150, a protective layer 155, and a cathode 160. Cathode 160 is acompound cathode having a first conductive layer 162 and a secondconductive layer 164. Device 100 may be fabricated by depositing thelayers described, in order. The properties and functions of thesevarious layers, as well as example materials, are described in moredetail in U.S. Pat. No. 7,279,704 at cols. 6-10, which are incorporatedby reference.

More examples for each of these layers are available. For example, aflexible and transparent substrate-anode combination is disclosed inU.S. Pat. No. 5,844,363, which is incorporated by reference in itsentirety. An example of a p-doped hole transport layer is m-MTDATA dopedwith F.sub.4-TCNQ at a molar ratio of 50:1, as disclosed in U.S. PatentApplication Publication No. 2003/0230980, which is incorporated byreference in its entirety. Examples of emissive and host materials aredisclosed in U.S. Pat. No. 6,303,238 to Thompson et al., which isincorporated by reference in its entirety. An example of an n-dopedelectron transport layer is BPhen doped with Li at a molar ratio of 1:1,as disclosed in U.S. Patent Application Publication No. 2003/0230980,which is incorporated by reference in its entirety. U.S. Pat. Nos.5,703,436 and 5,707,745, which are incorporated by reference in theirentireties, disclose examples of cathodes including compound cathodeshaving a thin layer of metal such as Mg:Ag with an overlyingtransparent, electrically-conductive, sputter-deposited ITO layer. Thetheory and use of blocking layers is described in more detail in U.S.Pat. No. 6,097,147 and U.S. Patent Application Publication No.2003/0230980, which are incorporated by reference in their entireties.Examples of injection layers are provided in U.S. Patent ApplicationPublication No. 2004/0174116, which is incorporated by reference in itsentirety. A description of protective layers may be found in U.S. PatentApplication Publication No. 2004/0174116, which is incorporated byreference in its entirety.

FIG. 2 shows an inverted OLED 200. The device includes a substrate 210,a cathode 215, an emissive layer 220, a hole transport layer 225, and ananode 230. Device 200 may be fabricated by depositing the layersdescribed, in order. Because the most common OLED configuration has acathode disposed over the anode, and device 200 has cathode 215 disposedunder anode 230, device 200 may be referred to as an “inverted” OLED.Materials similar to those described with respect to device 100 may beused in the corresponding layers of device 200. FIG. 2 provides oneexample of how some layers may be omitted from the structure of device100.

The simple layered structure illustrated in FIGS. 1 and 2 is provided byway of non-limiting example, and it is understood that embodiments ofthe invention may be used in connection with a wide variety of otherstructures. The specific materials and structures described areexemplary in nature, and other materials and structures may be used.Functional OLEDs may be achieved by combining the various layersdescribed in different ways, or layers may be omitted entirely, based ondesign, performance, and cost factors. Other layers not specificallydescribed may also be included. Materials other than those specificallydescribed may be used. Although many of the examples provided hereindescribe various layers as comprising a single material, it isunderstood that combinations of materials, such as a mixture of host anddopant, or more generally a mixture, may be used. Also, the layers mayhave various sublayers. The names given to the various layers herein arenot intended to be strictly limiting. For example, in device 200, holetransport layer 225 transports holes and injects holes into emissivelayer 220, and may be described as a hole transport layer or a holeinjection layer. In one embodiment, an OLED may be described as havingan “organic layer” disposed between a cathode and an anode. This organiclayer may comprise a single layer, or may further comprise multiplelayers of different organic materials as described, for example, withrespect to FIGS. 1 and 2.

Structures and materials not specifically described may also be used,such as OLEDs comprised of polymeric materials (PLEDs) such as disclosedin U.S. Pat. No. 5,247,190 to Friend et al., which is incorporated byreference in its entirety. By way of further example, OLEDs having asingle organic layer may be used. OLEDs may be stacked, for example asdescribed in U.S. Pat. No. 5,707,745 to Forrest et al, which isincorporated by reference in its entirety. The OLED structure maydeviate from the simple layered structure illustrated in FIGS. 1 and 2.For example, the substrate may include an angled reflective surface toimprove out-coupling, such as a mesa structure as described in U.S. Pat.No. 6,091,195 to Forrest et al., and/or a pit structure as described inU.S. Pat. No. 5,834,893 to Bulovic et al., which are incorporated byreference in their entireties.

Unless otherwise specified, any of the layers of the various embodimentsmay be deposited by any suitable method. For the organic layers,preferred methods include thermal evaporation, ink-jet, such asdescribed in U.S. Pat. Nos. 6,013,982 and 6,087,196, which areincorporated by reference in their entireties, organic vapor phasedeposition (OVPD), such as described in U.S. Pat. No. 6,337,102 toForrest et al., which is incorporated by reference in its entirety, anddeposition by organic vapor jet printing (OVJP), such as described inU.S. patent application Ser. No. 10/233,470, which is incorporated byreference in its entirety. Other suitable deposition methods includespin coating and other solution based processes. Solution basedprocesses are preferably carried out in nitrogen or an inert atmosphere.For the other layers, preferred methods include thermal evaporation.Preferred patterning methods include deposition through a mask, coldwelding such as described in U.S. Pat. Nos. 6,294,398 and 6,468,819,which are incorporated by reference in their entireties, and patterningassociated with some of the deposition methods such as ink jet and OVJD.Other methods may also be used. The materials to be deposited may bemodified to make them compatible with a particular deposition method.For example, substituents such as alkyl and aryl groups, branched orunbranched, and preferably containing at least 3 carbons, may be used insmall molecules to enhance their ability to undergo solution processing.Substituents having 20 carbons or more may be used, and 3-20 carbons isa preferred range. Materials with asymmetric structures may have bettersolution processibility than those having symmetric structures, becauseasymmetric materials may have a lower tendency to recrystallize.Dendrimer substituents may be used to enhance the ability of smallmolecules to undergo solution processing.

Devices fabricated in accordance with embodiments of the invention maybe incorporated into a wide variety of consumer products, including flatpanel displays, computer monitors, televisions, billboards, lights forinterior or exterior illumination and/or signaling, heads up displays,fully transparent displays, flexible displays, laser printers,telephones, cell phones, personal digital assistants (PDAs), laptopcomputers, digital cameras, camcorders, viewfinders, micro-displays,vehicles, a large area wall, theater or stadium screen, or a sign.Various control mechanisms may be used to control devices fabricated inaccordance with the present invention, including passive matrix andactive matrix. Many of the devices are intended for use in a temperaturerange comfortable to humans, such as 18 degrees C. to 30 degrees C., andmore preferably at room temperature (20-25 degrees C.).

The materials and structures described herein may have applications indevices other than OLEDs. For example, other optoelectronic devices suchas organic solar cells and organic photodetectors may employ thematerials and structures. More generally, organic devices, such asorganic transistors, may employ the materials and structures.

The terms halo, halogen, alkyl, cycloalkyl, alkenyl, alkynyl, arylkyl,heterocyclic group, aryl, aromatic group, and heteroaryl are known tothe art, and are defined in U.S. Pat. No. 7,279,704 at cols. 31-32,which are incorporated herein by reference.

A novel class of organometallic compounds is provided. The compoundscomprise a phenylquinoline or phenylisoquinoline ligand having thequinoline or isoquinoline linked to the phenyl ring of thephenylquinoline or phenylisoquinoline, respectively, via two carbonatoms, e.g., a linked phenylquinoline or linked phenylisoquinoline (asillustrated in FIG. 3). In addition, the ligand also includes at leastone substituent other than hydrogen and deuterium on the quinoline,isoquinoline or two carbon atoms linking the quinoline or isoquinolineto the aromatic ring, i.e., bulky substituent. These compounds may beused as red emitters in phosphorescent OLEDs. In particular, thesecompounds may provide stable, narrow and efficient red emission as aresult of the rigidification and addition of a bulky substituent.

The compounds disclosed herein may provide narrow red emission as aresult of rigidification, which may narrow the EL spectrum. The spectrumat half maximum (FWHW) of an organic molecule may narrow as themolecules become more rigid. The compounds disclosed herein are mademore rigid by linking the top portion of the ligand, e.g., a quinolineor isoquinoline, to the bottom portion of the ligand, e.g., phenyl ring.For example, the compounds may include a linked phenylquinoline orlinked phenylisoquinoline. In particular, a compound comprising a2-phenylquinoline ligand in which the quinoline has been linked to thephenyl ring may have a narrower EL spectrum. A narrow EL spectrum is adesirable property of electroluminescent materials for use in an OLED.

As discussed above, a two carbon atom linker links the quinoline orisoquinoline to the phenyl ring of the phenylquinoline orphenylisoquinoline. Without being bound by theory, it is believed thatusing only carbon atoms as linkers may provide better device stability,i.e., longer device lifetime, when compared to other linkers, such asthose with oxygen atoms. Additionally, it is believed that two atoms inthe linker backbone, rather than one atom, is desirable. One atom linkermay be too small, resulting in an increased coordinating binding angleof the ligand to metal on the other side of the ligand, which may reducethe bond strength of metal to ligand, and, in turn, decrease thestability of the metal complex.

Moreover, the compounds disclosed herein may provide stable andefficient red emission as a result of having a substituent other thanhydrogen and deuterium on the quinoline, isoquinoline or two carbonatoms in the linked ligand. Without being bound by theory, it isbelieved that the addition of a bulky substituent to the linked ligandmay prevent aggregation and self quenching in the compound, therebyproviding higher device efficiency.

Without being bound by theory, it may be particularly advantageous tohave an alkyl substituent as the bulky group on the linked ligandbecause alkyls offer a wide range of tunability. In particular, an alkylsubstituent may be useful for tuning the evaporation temperature,solubility, energy levels, device efficiency and narrowness of theemission spectrum of the compound. Additionally, alkyl groups can bestable functional groups chemically and in device operation. Forexample, a linked ligand comprising an alkyl substituent on thequinoline may provide increased efficiency.

Organometallic compounds comprising a phenylquinoline orphenylisoquinoline ligand containing a quinoline or isoquinoline linkedto the phenyl ring of the phenylquinoline or phenylisoquinoline,respectively, via two carbon atoms are provided (as illustrated in FIG.4).

The compounds also comprise a bulky substituent, i.e., not hydrogen ordeuterium, on the quinoline, isoquinoline, or linker. The compounds havethe formula M(L₁)_(x)(L₂)_(y)(L₃)_(z).

The ligand L₁ is

The ligand L₂ is

The ligand L₃ is a third ligand.

Each L₁, L₂ and L₃ can be the same or different. M is a metal having anatomic number greater than 40. Preferably, M is Ir. x is 1, 2, or 3. yis 0, 1, or 2. z is 0, 1, or 2. x+y+z is the oxidation state of themetal M. R is a carbocyclic or heterocyclic ring fused to the pyridine.R is optionally further substituted with R′. A, B, and C are eachindependently a 5 or 6-membered carbocyclic or heterocyclic ring. R′,R_(Z), R_(A), R_(B), and R_(C) may represent mono, di, tri, or tetrasubstitutions. Each of R₁, R₂, R₃, R₄, R′, R_(Z), R_(A), R_(B), andR_(C) are independently selected from the group consisting of hydrogen,deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy,aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl,aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof. At least one of R₁, R₂, R₃, R₄, and R′ is not hydrogen ordeuterium. Any two adjacent R₁, R₂, R₃, R₄, and R′ are optionally linkedto form an alkyl ring.

For the compounds disclosed herein, a bulky substituent is present onthe quinoline, isoquinoline or two carbon atoms in the linked ligand.The bulky group may be a halide, alkyl, cycloalkyl, heteroalkyl,arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl,heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylicacids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl,phosphino, and combinations thereof, i.e., bulky group is a substituentother than hydrogen or deuterium. Without being bound by theory, it isbelieved that the bulky substituent is least likely to affect theemission color of the compound If it is placed at one or more of the R₁,R₂, R₃, R₄, and R′ positions.

In one aspect, at least one of R₁, R₂, R₃, R₄, and R′ is an alkyl. Inanother aspect, R′ is not hydrogen or deuterium. Preferably, at leastone of R₁, R₂, R₃, R₄, and R′ is an alkyl having more than 2 carbonatoms. More preferably, at least one of R₁, R₂, R₃, R₄, and R′ isisobutyl.

In one aspect, L₃ is a monoanionic bidentate ligand.

In another aspect, L₃ is

and R′₁, R′₂, and R′₃ are each independently selected from the groupconsisting of hydrogen, deuterium, halide, alkyl, cycloalkyl,heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl,cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl,carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl,sulfonyl, phosphino, and combinations thereof. Preferably, R′₂ ishydrogen. More preferably, at least one of R′₁, R′₂, and R′₃ contains abranched alkyl moiety with branching at a position further than the αposition to the carbonyl group. Most preferably, at least one of R′₁ andR′₃ is isobutyl.

In one aspect, the compound has the formula:

R₅ and R₆ may represent mono, di, tri, or tetra substitutions. Each ofR₅ and R₆ are independently selected from the group consisting ofhydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl,alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl,alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester,nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, andcombinations thereof. At least one of R₁, R₂, R₃, R₄, and R₆ is nothydrogen or deuterium. m is 1, 2, or 3.

In another aspect, the compound has the formula:

R₅ and R₆ may represent mono, di, tri, or tetra substitutions. Each ofR₅ and R₆ are independently selected from the group consisting ofhydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl,alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl,alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester,nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, andcombinations thereof. At least one of R₁, R₂, R₃, R₄, and R₆ is nothydrogen or deuterium. m is 1, 2, or 3.

Generally, it is desirable to maintain red emission while improvingother properties of these compounds, such as evaporation temperature andsolubility. In some instances, it may be desirable for the compound tohave a less bulky substituent on ring A. Ring A, e.g., benzene, may besubstituted with hydrogen, deuterium, halide, alkyl, cycloalkyl,heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl,cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl,carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl,sulfonyl, phosphino, and combinations thereof, as discussed above.However, it is thought that placing a bulky substituent on ring A maycause a pronounced shift in the emission color of the compound. In someaspects, then, it is preferable to substitute ring A with less bulkychemical substituents to maintain good red emission while improvingother properties of the compound, such as evaporation temperature andsolubility.

In one aspect, the compound is homoleptic. In another aspect, thecompound is heteroleptic.

Specific non-limiting examples of organometallic compounds comprising aphenylquinoline or phenylisoquinoline ligand having the quinoline orisoquinoline linked to the phenyl of the phenylquinoline orphenylisoquinoline, respectively, via a 2 carbon atom linker areprovided. These compounds also comprise a bulky substituent on thequinoline, isoquinoline, or linker. In one aspect, the compound isselected from the group consisting of:

Preferably, the compound is:

Additionally, a first device comprising a first organic light emittingdevice is provided. The organic light emitting device further comprisesan anode, a cathode, and an organic layer, disposed between the anodeand the cathode. The organic layer further comprises a compound havingthe formula M(L₁)_(x)(L₂)_(y)(L₃)_(z).

The ligand L₁ is

The ligand L₂ is

The ligand L₃ is a third ligand.

Each L₁, L₂ and L₃ can be the same or different. M is a metal having anatomic number greater than 40. x is 1, 2, or 3. y is 0, 1, or 2. z is 0,1, or 2. x+y+z is the oxidation state of the metal M. R is a carbocyclicor heterocyclic ring fused to the pyridine ring. R is optionally furthersubstituted with R′. A, B, and C are each independently a 5 or6-membered carbocyclic or heterocyclic ring. R′, R_(Z), R_(A), R_(B),and R_(C) may represent mono, di, tri, or tetra substitutions. Each ofR₁, R₂, R₃, R₄, R′, R_(Z), R_(A), R_(B), and R_(C) are independentlyselected from the group consisting of hydrogen, deuterium, halide,alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino,silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl,acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl,sulfinyl, sulfonyl, phosphino, and combinations thereof. At least one ofR₁, R₂, R₃, R₄, and R′ is not hydrogen or deuterium. Any two adjacentR₁, R₂, R₃, R₄, and R′ are optionally linked to form an alkyl ring.

The various specific aspects discussed above for compounds having theformula M(L₁)_(x)(L₂)_(y)(L₃)_(z) are also applicable to a compoundhaving M(L₁)_(x)(L₂)_(y)(L₃)_(z) that is used in the first device. Inparticular, specific aspects of L₁, L₂, L₃, A, B, C, R_(A), R_(B), Rc,R_(Z), R, R′, R₁, R₂, R₃, R₄, R₅, R₆, R′₁, R′₂, R′₃, M, m Formula IIIand Formula IV of the compound having the formulaM(L₁)_(x)(L₂)_(y)(L₃)_(z) are also applicable to a compound havingM(L₁)_(x)(L₂)_(y)(L₃)_(z) that is used in the first device.

In one aspect, the first device is a consumer product. In anotheraspect, the first device is an organic light emitting device. In yetanother aspect, the first device comprises a lighting panel.

In one aspect, the organic layer is an emissive layer and the compoundis an emissive dopant. In another aspect, the organic layer furthercomprises a host. Preferably, the host is a metal 8-hydroxyquinolate.

Combination with Other Materials

The materials described herein as useful for a particular layer in anorganic light emitting device may be used in combination with a widevariety of other materials present in the device. For example, emissivedopants disclosed herein may be used in conjunction with a wide varietyof hosts, transport layers, blocking layers, injection layers,electrodes and other layers that may be present. The materials describedor referred to below are non-limiting examples of materials that may beuseful in combination with the compounds disclosed herein, and one ofskill in the art can readily consult the literature to identify othermaterials that may be useful in combination.

HIL/HTL:

A hole injecting/transporting material to be used in the presentinvention is not particularly limited, and any compound may be used aslong as the compound is typically used as a hole injecting/transportingmaterial. Examples of the material include, but not limit to: aphthalocyanine or porphryin derivative; an aromatic amine derivative; anindolocarbazole derivative; a polymer containing fluorohydrocarbon; apolymer with conductivity dopants; a conducting polymer, such asPEDOT/PSS; a self-assembly monomer derived from compounds such asphosphonic acid and sliane derivatives; a metal oxide derivative, suchas MoO_(x); a p-type semiconducting organic compound, such as1,4,5,8,9,12-Hexaazatriphenylenehexacarbonitrile; a metal complex, and across-linkable compounds.

Examples of aromatic amine derivatives used in HIL or HTL include, butnot limit to the following general structures:

Each of Ar¹ to Ar⁹ is selected from the group consisting aromatichydrocarbon cyclic compounds such as benzene, biphenyl, triphenyl,triphenylene, naphthalene, anthracene, phenalene, phenanthrene,fluorene, pyrene, chrysene, perylene, azulene; group consisting aromaticheterocyclic compounds such as dibenzothiophene, dibenzofuran,dibenzoselenophene, furan, thiophene, benzofuran, benzothiophene,benzoselenophene, carbazole, indolocarbazole, pyridylindole,pyrrolodipyridine, pyrazole, imidazole, triazole, oxazole, thiazole,oxadiazole, oxatriazole, dioxazole, thiadiazole, pyridine, pyridazine,pyrimidine, pyrazine, triazine, oxazine, oxathiazine, oxadiazine,indole, benzimidazole, indazole, indoxazine, benzoxazole, benzisoxazole,benzothiazole, quinoline, isoquinoline, cinnoline, quinazoline,quinoxaline, naphthyridine, phthalazine, pteridine, xanthene, acridine,phenazine, phenothiazine, phenoxazine, benzofuropyridine,furodipyridine, benzothienopyridine, thienodipyridine,benzoselenophenopyridine, and selenophenodipyridine; and groupconsisting 2 to 10 cyclic structural units which are groups of the sametype or different types selected from the aromatic hydrocarbon cyclicgroup and the aromatic heterocyclic group and are bonded to each otherdirectly or via at least one of oxygen atom, nitrogen atom, sulfur atom,silicon atom, phosphorus atom, boron atom, chain structural unit and thealiphatic cyclic group. Wherein each Ar is further substituted by asubstituent selected from the group consisting of hydrogen, deuterium,halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy,amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl,heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof.

In one aspect, Ar¹ to Ar⁹ is independently selected from the groupconsisting of:

k is an integer from 1 to 20; X¹ to X⁸ is C (including CH) or N; Ar¹ hasthe same group defined above.

Examples of metal complexes used in HIL or HTL include, but not limit tothe following general formula:

M is a metal, having an atomic weight greater than 40; (Y₁-Y²) is abidentate ligand, Y¹ and Y² are independently selected from C, N, O, P,and S; L is an ancillary ligand; m is an integer value from 1 to themaximum number of ligands that may be attached to the metal; and m+n isthe maximum number of ligands that may be attached to the metal.

In one aspect, (Y₁-Y²) is a 2-phenylpyridine derivative.

In another aspect, (Y₁-Y²) is a carbene ligand.

In another aspect, M is selected from Ir, Pt, Os, and Zn.

In a further aspect, the metal complex has a smallest oxidationpotential in solution vs. Fc⁺/Fc couple less than about 0.6 V.

Host:

The light emitting layer of the organic EL device of the presentinvention preferably contains at least a metal complex as light emittingmaterial, and may contain a host material using the metal complex as adopant material. Examples of the host material are not particularlylimited, and any metal complexes or organic compounds may be used aslong as the triplet energy of the host is larger than that of thedopant.

Examples of metal complexes used as host are preferred to have thefollowing general formula:

M is a metal; (Y³-Y⁴) is a bidentate ligand, Y³ and Y⁴ are independentlyselected from C, N, O, P, and S; L is an ancillary ligand; m is aninteger value from 1 to the maximum number of ligands that may beattached to the metal; and m+n is the maximum number of ligands that maybe attached to the metal.

In one aspect, the metal complexes are:

(O—N) is a bidentate ligand, having metal coordinated to atoms O and N.

In another aspect, M is selected from Ir and Pt.

In a further aspect, (Y³-Y⁴) is a carbene ligand.

Examples of organic compounds used as host are selected from the groupconsisting aromatic hydrocarbon cyclic compounds such as benzene,biphenyl, triphenyl, triphenylene, naphthalene, anthracene, phenalene,phenanthrene, fluorene, pyrene, chrysene, perylene, azulene; groupconsisting aromatic heterocyclic compounds such as dibenzothiophene,dibenzofuran, dibenzoselenophene, furan, thiophene, benzofuran,benzothiophene, benzoselenophene, carbazole, indolocarbazole,pyridylindole, pyrrolodipyridine, pyrazole, imidazole, triazole,oxazole, thiazole, oxadiazole, oxatriazole, dioxazole, thiadiazole,pyridine, pyridazine, pyrimidine, pyrazine, triazine, oxazine,oxathiazine, oxadiazine, indole, benzimidazole, indazole, indoxazine,benzoxazole, benzisoxazole, benzothiazole, quinoline, isoquinoline,cinnoline, quinazoline, quinoxaline, naphthyridine, phthalazine,pteridine, xanthene, acridine, phenazine, phenothiazine, phenoxazine,benzofuropyridine, furodipyridine, benzothienopyridine,thienodipyridine, benzoselenophenopyridine, and selenophenodipyridine;and group consisting 2 to 10 cyclic structural units which are groups ofthe same type or different types selected from the aromatic hydrocarboncyclic group and the aromatic heterocyclic group and are bonded to eachother directly or via at least one of oxygen atom, nitrogen atom, sulfuratom, silicon atom, phosphorus atom, boron atom, chain structural unitand the aliphatic cyclic group. Wherein each group is furthersubstituted by a substituent selected from the group consisting ofhydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl,alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl,alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester,nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, andcombinations thereof.

In one aspect, host compound contains at least one of the followinggroups in the molecule:

R¹ to R⁷ is independently selected from the group consisting ofhydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl,alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl,alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester,nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, andcombinations thereof, when it is aryl or heteroaryl, it has the similardefinition as Ar's mentioned above.

k is an integer from 0 to 20.

X¹ to X⁸ is selected from C (including CH) or N.

HBL:

A hole blocking layer (HBL) may be used to reduce the number of holesand/or excitons that leave the emissive layer. The presence of such ablocking layer in a device may result in substantially higherefficiencies as compared to a similar device lacking a blocking layer.Also, a blocking layer may be used to confine emission to a desiredregion of an OLED.

In one aspect, compound used in HBL contains the same molecule used ashost described above.

In another aspect, compound used in HBL contains at least one of thefollowing groups in the molecule:

k is an integer from 0 to 20; L is an ancillary ligand, m is an integerfrom 1 to 3.

ETL:

Electron transport layer (ETL) may include a material capable oftransporting electrons. Electron transport layer may be intrinsic(undoped), or doped. Doping may be used to enhance conductivity.Examples of the ETL material are not particularly limited, and any metalcomplexes or organic compounds may be used as long as they are typicallyused to transport electrons.

In one aspect, compound used in ETL contains at least one of thefollowing groups in the molecule:

R¹ is selected from the group consisting of hydrogen, deuterium, halide,alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino,silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl,acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl,sulfanyl, sulfonyl, phosphino, and combinations thereof, when it is arylor heteroaryl, it has the similar definition as Ar's mentioned above.

Ar¹ to Ar^(a) has the similar definition as Ar's mentioned above.

k is an integer from 0 to 20.

X¹ to X⁸ is selected from C (including CH) or N.

In another aspect, the metal complexes used in ETL contains, but notlimit to the following general formula:

(O—N) or (N—N) is a bidentate ligand, having metal coordinated to atomsO, N or N, N;

L is an ancillary ligand; m is an integer value from 1 to the maximumnumber of ligands that may be attached to the metal.

In any above-mentioned compounds used in each layer of the OLED device,the hydrogen atoms can be partially or fully deuterated.

In addition to and/or in combination with the materials disclosedherein, many hole injection materials, hole transporting materials, hostmaterials, dopant materials, exiton/hole blocking layer materials,electron transporting and electron injecting materials may be used in anOLED. Non-limiting examples of the materials that may be used in an OLEDin combination with materials disclosed herein are listed in Table 1below. Table 1 lists non-limiting classes of materials, non-limitingexamples of compounds for each class, and references that disclose thematerials.

TABLE 1 MATERIAL EXAMPLES OF MATERIAL PUBLICATIONS Hole injectionmaterials Phthalocyanine and porphryin compounds

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J. Lumin. 72-74, 985 (1997) CF_(x) Fluorohydrocarbon polymer

Appl. Phys. Lett. 78, 673 (2001) Conducting polymers (e.g., PEDOT:PSS,polyaniline, polypthiophene)

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EP1725079A1 Arylamines complexed with metal oxides such as molybdenumand tungsten oxides

SID Symposium Digest, 37, 923 (2006) WO2009018009 p-type semiconductingorganic complexes

US20020158242 Metal organometallic complexes

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Appl. Phys. Lett. 51, 913 (1987)

U.S. Pat. No. 5,061,569

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J. Mater. Chem. 3, 319 (1993)

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Adv. Mater. 6, 677 (1994), US20080124572 Triarylamine with(di)benzothiophene/ (di)benzofuran

US20070278938, US20080106190 Indolocarbazoles

Synth. Met. 111, 421 (2000) Isoindole compounds

Chem. Mater. 15, 3148 (2003) Metal carbene complexes

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Nature 395, 151 (1998)

US20060202194

WO2005014551

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Org. Electron. 1, 15 (2000) Aromatic fused rings

WO2009066779, WO2009066778, WO2009063833, US20090045731, US20090045730,WO2009008311, US20090008605, US20090009065 Zinc complexes

WO2009062578 Green hosts Arylcarbazoles

Appl. Phys. Lett. 78, 1622 (2001)

US20030175553

WO2001039234 Aryltriphenylene compounds

US20060280965

US20060280965

WO2009021126 Donor acceptor type molecules

WO2008056746 Aza-carbazole/DBT/DBF

JP2008074939 Polymers (e.g., PVK)

Appl. Phys. Lett. 77, 2280 (2000) Spirofluorene compounds

WO2004093207 Metal phenoxybenzooxazole compounds

WO2005089025

WO2006132173

JP200511610 Spirofluorene-carbazole compounds

JP2007254297

JP2007254297 Indolocabazoles

WO2007063796

WO2007063754 5-member ring electron deficient heterocycles (e.g.,triazole, oxadiazole)

J. Appl. Phys. 90, 5048 (2001)

WO2004107822 Tetraphenylene complexes

US20050112407 Metal phenoxypyridine compounds

WO2005030900 Metal coordination complexes (e.g., Zn, Al withN{circumflex over ( )}N ligands)

US20040137268, US20040137267 Blue hosts Arylcarbazoles

Appl. Phys. Lett, 82, 2422 (2003)

US20070190359 Dibenzothiophene/ Dibenzofuran-carbazole compounds

WO2006114966, US20090167162

US20090167162

WO2009086028

US20090030202, US20090017330 Silicon aryl compounds

US20050238919

WO2009003898 Silicon/Germanium aryl compounds

EP2034538A Aryl benzoyl ester

WO2006100298 High triplet metal organometallic complex

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Nature 395, 151 (1998) Iridium(III) organometallic complexes

Appl. Phys. Lett. 78, 1622 (2001)

US2006835469

US2006835469

US20060202194

US20060202194

US20070087321

US20070087321

Adv. Mater. 19, 739 (2007)

WO2009100991

WO2008101842 Platinum(II) organometallic complexes

WO2003040257 Osminum(III) complexes

Chem. Mater. 17, 3532 (2005) Ruthenium(II) complexes

Adv. Mater. 17, 1059 (2005) Rhenium (I), (II), and (III) complexes

US20050244673 Green dopants Iridium(III) organometallic complexes

  and its derivatives Inorg. Chem. 40, 1704 (2001)

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U.S. Pat. No. 7,332,232

US20090108737

US20090039776

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U.S. Pat. No. 6,687,266

Chem. Mater. 16, 2480 (2004)

US20070190359

US20060008670 JP2007123392

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Angew. Chem. Int. Ed. 2006, 45, 7800

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US20090165846

US20080015355 Monomer for polymeric metal organometallic compounds

U.S. Pat. No. 7,250,226, U.S. Pat. No. 7,396,598 Pt(II) organometalliccomplexes, including polydentated ligands

Appl. Phys. Lett. 86, 153505 (2005)

Appl. Phys. Lett. 86, 153505 (2005)

Chem. Lett. 34, 592 (2005)

WO2002015645

US20060263635 Cu complexes

WO2009000673 Gold complexes

Chem. Commun. 2906 (2005) Rhenium(III) complexes

Inorg. Chem. 42, 1248 (2003) Deuterated organometallic complexes

US20030138657 Organometallic complexes with two or more metal centers

US20030152802

U.S. Pat. No. 7,090,928 Blue dopants Iridium(III) organometalliccomplexes

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WO2006009024

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U.S. Pat. No. 7,534,505

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Chem. Mater. 18, 5119 (2006)

Inorg. Chem. 46, 4308 (2007)

WO2005123873

WO2005123873

WO2007004380

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U.S. Pat. No. 7,279,704

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Appl. Phys. Lett. 74, 1361 (1999) Platinum(II) complexes

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Appl. Phys. Lett. 75, 4 (1999)

Appl. Phys. Lett. 79, 449 (2001) Metal 8-hydroxyquinolates (e.g., BAlq)

Appl. Phys. Lett. 81, 162 (2002) 5-member ring electron deficientheterocycles such as triazole, oxadiazole, imidazole, benzoimidazole

Appl. Phys. Lett. 81, 162 (2002) Triphenylene compounds

US20050025993 Fluorinated aromatic compounds

Appl. Phys. Lett. 79, 156 (2001) Phenothiazine-S-oxide

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EXPERIMENTAL Compound Examples Example 1 Synthesis of Compound 9

Synthesis of (2-amino-6-chlorophenyl)methanol

2-Amino-6-chlorobenzoic acid (25.0 g, 143 mmol) was dissolved in 120 mLof anhydrous THF in a 500 mL 2 neck round bottom flask. The solution wascooled in an ice-water bath. 215 mL of 1.0 M lithium aluminum hydride(LAH) THF solution was then added dropwise. After all of the LAH wasadded, the reaction mixture was allowed to warm up to room temperatureand stirred at room temperature for overnight. ˜10 mL of water was addedto the reaction mixture followed by 7 g 15% NaOH. An additional 20 g ofwater was added to the reaction mixture. Decant the organic THF phaseand the solid was added with ethyl acetate. ˜200 mL and stirring andcombined ethyl acetate organic portion and THF portion and added Na₂SO₄drying agent. The mixture was filtered and evaporated. ˜20 g yellowsolid was obtained without further purification for next step reaction.

Synthesis of 8-chloro-2,4-dimethyl-5,6-dihydrobenzo[c] acridine

(2-Amino-6-chlorophenyl)methanol (16 g, 101 mmol),5,7-dimethyl-3,4-dihydronaphthalen-1(2H)-one (20.0 g, 111 mmol),RuCl₂(PPh₃)₃ (0.971 g, 1.01 mmol), and KOH (5.7 g, 101 mmol) wererefluxed in 200 mL of toluene for 12 h. Water was collected from thereaction using a Dean-stark trap. The reaction mixture was allowed tocool to room temperature and filtered through a silica gel plug andeluted with dichloromethane. The product was washed by methanol andrecrystallized from hexane to obtain ˜20 gram of the desired productwhich was confirmed by GC-MS.

Synthesis of 8-isobutyl-2,4-dimethyl-5,6-dihydrobenzo[c]acridine

8-chloro-2,4-dimethyl-5,6-dihydrobenzo[c]acridine (15.0 g, 51.1 mmol),isobutylboronic acid (7.8 g, 77 mmol),dicyclohexyl(2′,6′-dimethoxy-[1,1′-biphenyl]-2-yl)phosphine (1.6 g, 4.08mmol) potassium phosphate monohydrate (41.2 g, 179 mmol) were mixed in300 mL of toluene. The system was degassed for 20 minutes. Pd₂(dba)₃(0.93 g, 1.02 mmol) was then added and the system was refluxedovernight. After cooling to room temperature, the reaction mixture wasfiltered through a Celite® plug and eluted with 30% ethyl acetate intoluene. ˜19.5 crude liquid was obtained. The crude product wasrecystalized from 5% acetone in hexane to obtain ˜14.9 g pure product(99.6%) which was confirmed by GC-MS.

Synthesis of Iridium Dimer.

A mixture of 8-isobutyl-2,4-dimethyl-5,6-dihydrobenzo[c]acridine (11.5g, 36.5 mmol), IrCl₃.4H₂O (4.5 g, 12.2 mmol), 2-ethoxyethanol (90 mL)and water (30 mL) was refluxed under nitrogen overnight. The reactionmixture was filtered and washed with MeOH (3×20 mL). ˜9 g of dimer wasobtained after vacuum drying. The dimer was used for the next stepwithout further purification.

Synthesis of Compound 9.

Dimer (3.5 g, 2.07 mmol), pentane-2,4-dione (2.07 g, 20.7 mmol), Na₂CO₃(2.19 g, 20.7 mmol) and 2-ethoxyethanol (100 mL) were stirred at roomtemperature for 24 h. The precipitate was filtered and washed withmethanol. The solid was further purified by passing it through a silicagel plug (that was pretreated with 15% TEA in hexanes) and eluted withmethylene chloride. 0.6 g of product Compound 9 was obtained afterpurification. The compound was confirmed by LC-MS.

Example 2 Synthesis of Compound 10

Compound 10 was synthesized in same way as Compound 9, and confirmed byLC-MS.

Device Examples

All example devices were fabricated by high vacuum (<10⁻⁷ Ton) thermalevaporation. The anode electrode is 1200 Å of indium tin oxide (ITO).The cathode consisted of 10 Å of LiF followed by 1,000 Å of Al. Alldevices are encapsulated with a glass lid sealed with an epoxy resin ina nitrogen glove box (<1 ppm of H₂O and O₂) immediately afterfabrication, and a moisture getter was incorporated inside the package.

The organic stack of the Device Examples consisted of sequentially, fromthe ITO surface, 100 Å of Compound A as the hole injection layer (HIL),300 Å of 4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (α-NPD) as thehole transporting layer (HTL), 300 Å of the invention compound doped inBAlq as host with 4, 6 or 8 wt % of an Ir phosphorescent compound as theemissive layer (EML), 500 or 550 Å of Alg₃ (tris-8-hydroxyquinolinealuminum) as the ETL.

Comparative Device Examples with Compound B was fabricated similarly tothe Device Examples, except that Compound B is used as the emitter inthe EML.

As used herein, Compound A, Compound B and other compounds used in thedevice examples have the following structures:

The device structures are summarized in Table 2, and the device data issummarized in Table 3. Cmpd. is an abbreviation of Compound. Ex. is anabbreviation of Example. Comp. Ex. is an abbreviation of ComparativeExample.

TABLE 2 Example HIL HTL EML (doping %) ETL Ex. 1 Compound NPD BalqCompound 10 Alq A 7% Ex. 2 Compound NPD Balq Compound 9 Alq A 8% Comp.Compound NPD Balq Compound B Alq Ex. 1 A 8%

TABLE 3 At 2000 At 1000 nits nits λ_(max) FWHM Voltage LE EQE PELT_(97%) Cmpd. x y [nm] [nm] [V] [cd/A] [%] [lm/W] [Hr] Ex. 1 0.6490.348 612 54 8.9 12.5 10.1 4.4 29.9 Ex. 2 0.656 0.341 616 62 8.8 8.5 8.03.0 8.5 Comp. Ex. 1 0.651 0.346 612 60 9.7 9.9 8.6 3.2 9.5

Table 3 is a summary of the device data. The luminous efficiency (LE),external quantum efficiency (EQE) and power efficiency (PE) weremeasured at 1000 nits, while the lifetime (LT_(97%)) was defined as thetime required for the device to decay to 97% of its initial luminance at2000 nits under a constant current density.

As seen from Table 3, the EQE measured at 1000 nits for a devicecomprising Compound 10 is 17% higher than the EQE measured for a devicecomprising Compound B. Additionally, the EL spectral full width at halfmaximum (FWHW) of Compound 10 is also narrower than the FWHM of CompoundB, i.e, FWHM of Compound 10 is 54 nm, while the FWHM of Compound B is 60nm. The FWHM of Compound 9, however, is similar to the FWHM of CompoundB. It is a desirable device property to have a narrow FWHM. Theseresults indicate that Compound 10 is a more efficient red emitter thanCompounds B with a desirable narrower FWHM.

Compound 10 also has a longer lifetime than Compound B, i.e., the LT₉₇%measured at room temperature for Compound 10 is about three times aslong as the LT₉₇% measured at room temperature for Compound B. Compound10 differs from Compound B in that it has a bulkier substituent onquinoline ring. Therefore, devices comprising a compound with asubstituent on the quinoline ring may have significantly improvedperformance.

It is understood that the various embodiments described herein are byway of example only, and are not intended to limit the scope of theinvention. For example, many of the materials and structures describedherein may be substituted with other materials and structures withoutdeviating from the spirit of the invention. The present invention asclaimed may therefore include variations from the particular examplesand preferred embodiments described herein, as will be apparent to oneof skill in the art. It is understood that various theories as to whythe invention works are not intended to be limiting.

1. A compound having the formula M(L₁)_(x)(L₂)_(y)(L₃)_(z): wherein theligand L₁ is

wherein the ligand L₂ is

wherein the ligand L₃ is a third ligand; wherein each L₁, L₂ and L₃ canbe the same or different; wherein M is a metal having an atomic numbergreater than 40; wherein x is 1, 2, or 3; wherein y is 0, 1, or 2;wherein z is 0, 1, or 2; wherein x+y+z is the oxidation state of themetal M; wherein R is a carbocyclic or heterocyclic ring fused to thepyridine ring; R is optionally further substituted with R′; wherein A,B, and C are each independently a 5 or 6-membered carbocyclic orheterocyclic ring; wherein R′, R_(Z), R_(A), R_(B), and R_(C) mayrepresent mono, di, tri, or tetra substitutions; wherein each of R₁, R₂,R₃, R₄, R′, R_(Z), R_(A), R_(B), and R_(C) are independently selectedfrom the group consisting of hydrogen, deuterium, halide, alkyl,cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl,alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl,carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl,sulfonyl, sulfonyl, phosphino, and combinations thereof; wherein atleast one of R₁, R₂, R₃, R₄, and R′ is not hydrogen or deuterium; andwherein any two adjacent R₁, R₂, R₃, R₄, and R′ are optionally linked toform an alkyl ring.
 2. The compound of claim 1, wherein M is Ir.
 3. Thecompound of claim 1, wherein at least one of R₁, R₂, R₃, R₄, and R′ isan alkyl.
 4. The compound of claim 1, wherein at least one of R₁, R₂,R₃, R₄, and R′ is an alkyl having more than 2 carbon atoms.
 5. Thecompound of claim 1, wherein at least one of R₁, R₂, R₃, R₄, and R′ isisobutyl.
 6. The compound of claim 1, wherein R′ is not hydrogen ordeuterium.
 7. The compound of claim 1, wherein L₃ is a monoanionicbidentate ligand.
 8. The compound of claim 1, wherein L₃ is

and wherein R′₁, R′₂, and R′₃ are each independently selected from thegroup consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl,heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl,cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl,carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfanyl,sulfonyl, phosphino, and combinations thereof.
 9. The compound of claim8, wherein at least one of R′₁, R′₂, and R′₃ contains a branched alkylmoiety with branching at a position further than the α position to thecarbonyl group.
 10. The compound of claim 8, wherein at least one of R′₁and R′₃ is isobutyl.
 11. The compound of claim 8, wherein R′₂ ishydrogen.
 12. The compound of claim 1, wherein the compound has theformula:

wherein R₅ and R₆ may represent mono, di, tri, or tetra substitutions;wherein each of R₅ and R₆ are independently selected from the groupconsisting of hydrogen, deuterium, halide, alkyl, cycloalkyl,heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl,cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl,carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl,sulfonyl, phosphino, and combinations thereof; wherein at least one ofR₁, R₂, R₃, R₄, and R₆ is not hydrogen or deuterium; and wherein m is 1,2, or
 3. 13. The compound of claim 1, wherein the compound has theformula:

wherein R₅ and R₆ may represent mono, di, tri, or tetra substitutions;wherein each of R₅ and R₆ are independently selected from the groupconsisting of hydrogen, deuterium, halide, alkyl, cycloalkyl,heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl,cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl,carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl,sulfonyl, phosphino, and combinations thereof; wherein at least one ofR₁, R₂, R₃, R₄, and R₆ is not hydrogen or deuterium; and wherein m is 1,2, or
 3. 14. The compound of claim 1, wherein the compound ishomoleptic.
 15. The compound of claim 1, wherein the compound isheteroleptic.
 16. The compound of claim 1, wherein the compound isselected from the group consisting of:


17. The compound of claim 1, wherein the compound is selected from thegroup consisting of:


18. A first device comprising a first organic light emitting device,further comprising: an anode; a cathode; and an organic layer, disposedbetween the anode and the cathode, comprising a compound having theformula M(L₁)_(x)(L₂)_(y)(L₃)_(z): wherein the ligand L₁ is

wherein the ligand L₂ is

wherein the ligand L₃ is a third ligand; wherein each L₁, L₂ and L₃ canbe the same or different; wherein M is a metal having an atomic numbergreater than 40; wherein x is 1, 2, or 3; wherein y is 0, 1, or 2;wherein z is 0, 1, or 2; wherein x+y+z is the oxidation state of themetal M; wherein R is a carbocyclic or heterocyclic ring fused to thepyridine ring; R is optionally further substituted with R′; wherein A,B, and C are each independently a 5 or 6-membered carbocyclic orheterocyclic ring; wherein R′, R_(Z), R_(A), R_(B), and R_(C) mayrepresent mono, di, tri, or tetra substitutions; wherein each of R₁, R₂,R₃, R₄, R′, R_(Z), R_(A), R_(B), and R_(C) are independently selectedfrom the group consisting of hydrogen, deuterium, halide, alkyl,cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl,alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl,carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl,sulfinyl, sulfonyl, phosphino, and combinations thereof; wherein atleast one of R₁, R₂, R₃, R₄, and R′ is not hydrogen or deuterium; andwherein any two adjacent R₁, R₂, R₃, R₄, and R′ are optionally linked toform an alkyl ring.
 19. The first device of claim 18, wherein the firstdevice is a consumer product.
 20. The first device of claim 18, whereinthe first device is an organic light emitting device.
 21. The firstdevice of claim 18, wherein the first device comprises a lighting panel.22. The first device of claim 18, wherein the organic layer is anemissive layer and the compound is an emissive dopant.
 23. The firstdevice of claim 18, wherein the organic layer further comprises a host.24. The first device of claim 23, wherein the host is a metal8-hydroxyquinolate.